Physical Description

Physically Identifying T. gratilla

As an Echinoderm the collectorurchin displays pentamerous symmetry with their oral opening facing thesubstrate and the anus facing the open surface. Adult T. gratilla canrange in size from 100mm-150mm in size depending on their current geographic location (WoRMS 2014). T.gratilla adults also exhibit no sexual dimorphism between males and females and can only be distinguished when dissected or during spawning periods (Lawrence & Agatsuma 2007).

Typical Collector Urchin ariel view of individual, tube feet are not extended. Photo Stephanie Lyon

Collector urchins aretypically dark in colour with blue and purple hues common amongst the species.  The bases of their spines are generally white with the tips fusing into orange, however in some individuals the spinescan be completely orange (WoRMS 2014).  

     
Variances in spine colors between idividuals. Photo Stephanie Lyon

The calcareous surface a dark brown colour contrasts against the bright spines.  Tube feet are also white with the tips ranging from green too purple, as well as white pedicellariae that are locatedalongside the many feet (WoRMS 2014). 


​Urchin extending tube feet. Photo Stephanie Lyon